Look for legacy update directory for 1.2.0 -> 2.x.x updates

StabilityMatrix.Avalonia/Program.cs

@@ -70,9 +70,13 @@ public class Program
 
     private static void HandleUpdateReplacement()
     {
-        // Check if we're in the named update folder
-        if (Compat.AppCurrentDir.Parent is {Name: UpdateHelper.UpdateFolderName} parentDir)
+        // Check if we're in the named update folder or the legacy update folder for 1.2.0 -> 2.0.0
+        if (Compat.AppCurrentDir is {Name: UpdateHelper.UpdateFolderName} or {Name: "Update"})
         {
+            var parentDir = Compat.AppCurrentDir.Parent;
+            if (parentDir is null) 
+                return;
+            
             var retryDelays = Backoff.DecorrelatedJitterBackoffV2(
                 TimeSpan.FromMilliseconds(350), retryCount: 5);
 
@@ -112,6 +116,21 @@ public class Program
                 logger.Error(e, "Failed to delete update file");
             }
         }
+        
+        // for 1.2.0 -> 2.0.0 update
+        var legacyUpdateDir = Compat.AppCurrentDir.JoinDir("Update");
+        if (legacyUpdateDir.Exists)
+        {
+            try
+            {
+                legacyUpdateDir.Delete(true);
+            }
+            catch (Exception e)
+            {
+                var logger = LogManager.GetCurrentClassLogger();
+                logger.Error(e, "Failed to delete legacy update file");
+            }
+        }
     }
     
     private static void ConfigureSentry()